As part of the search for anticancer agents from plant sources, it is planned in this study to engage in a chemical study of the plants Coronilla varia, Strychnos henningsii, Croton texensis and Centaurea solstitialis whose extracts have shown activity against 9KB or P-388 leukemia in the mouse. This research will involve the isolation of the active constituents of these plants, guided by bioassay, and subsequent studies to determine the structures of the active components. At the same time this project involves synthetic studies aimed at the preparation of lactones as potential anticancer agents. The synthetic approaches will be guided by structure-activity relationships established by a consideration of previously isolated plant-derived anticancer agents.